Unbalanced ribosome assembly in Saccharomyces cerevisiae expressing mutant 5 S rRNAs

• Published in: The Journal of biological chemistry Vol. 267; no. 23; pp. 16177 - 16181
• Main Authors: Van Ryk, D.I. (University of Guelph, Guelph, Ontario, Canada), Lee, Y, Nazar, R.N
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 15.08.1992
• Subjects: ARN RIBOSOMAL; ARN RIBOSOMIAL; Base Sequence; Biological and medical sciences; Cell structures and functions; CELLULE; CELULAS; Cloning, Molecular; CRECIMIENTO; CROISSANCE; Escherichia coli - genetics; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; Molecular and cellular biology; Molecular Sequence Data; Mutagenesis, Site-Directed; MUTANT; MUTANTES; Nucleic Acid Conformation; Polyribosomes - metabolism; Protein Biosynthesis; RIBOSOMAS; RIBOSOME; Ribosomes - metabolism; RNA, Ribosomal, 5S - biosynthesis; RNA, Ribosomal, 5S - genetics; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; SINTESIS DE PROTEINAS; SYNTHESE PROTEIQUE; Fungi; Ribosome; In vitro translation; Structure activity relation; Molecular assembly; Ribosomal RNA; Ascomycetes; Mutation; Saccharomyces cerevisiae; 5S-RNA; Thallophyta
• DOI: 10.1016/S0021-9258(18)41983-7
• ISSN: 0021-9258

Mutant 5 S rRNA genes were expressed in Saccharomyces cerevisiae to further define the function of the ribosomal 5 S RNA. RNA synthesis and utilization were assayed using previously constructed markers which have been shown to be functionally. neutral and easily detected by gel electrophoresis. Most mutations were found not to affect the growth rate because they were poorly expressed or could be accommodated effectively in the ribosomal structure. Two of the mutants, Y5A99U56U57 and Y5U90i5 adversely affected cell growth as well as protein synthesis in vitro. Polyribosome profiles in both of these mutants were substantially shorter, and an analysis of the ribosomal subunit composition revealed a significant imbalance with a 25-35% excess in 40 S subunits. Kinetic analyses of RNA labeling indicated very low cellular levels of mutant RNA either because it was poorly expressed (Y5U90i5) or rapidly degraded before being incorporated into mature 60 subunits (Y5A99U56U57). The results suggest that the 5 S RNA is required for the assembly of stable ribosomal 60 S subunits and raise the possibility that this RNA or, more likely, its corresponding ribonucleoprotein complex is critical for subunit assembly or even RNA processing